Re: [PATCH v4] OvmfPkg/ResetVector: Depend on PCD values of the page tables.

[Jordan Justen <jordan.l.justen@intel.com>]

On 2016-11-04 15:27:48, Laszlo Ersek wrote:
> On 11/04/16 14:32, Marvin Häuser wrote:
> > Currently, the value of the page tables' address is hard-coded in the
> > ResetVector. This patch replaces these values with a PCD dependency.
> > 
> > A check for the size has been added to alert the developer to rewrite
> > the ASM according to the new size, if it has been changed.
> > 
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
> > ---
> >  OvmfPkg/ResetVector/Ia32/PageTables64.asm | 23 ++++++++++----------
> >  OvmfPkg/ResetVector/ResetVector.inf       |  5 +++++
> >  OvmfPkg/ResetVector/ResetVector.nasmb     |  7 ++++++
> >  3 files changed, 24 insertions(+), 11 deletions(-)
> > 
> > diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> > index b5a4cf8d7187..6201cad1f5dc 100644
> > --- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> > +++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> > @@ -44,10 +44,11 @@ BITS    32
> >  SetCr3ForPageTables64:
> >  
> >      ;
> > -    ; For OVMF, build some initial page tables at 0x800000-0x806000.
> > +    ; For OVMF, build some initial page tables at
> > +    ; PcdOvmfSecPageTablesBase - (PcdOvmfSecPageTablesBase + 0x6000).
> >      ;
> > -    ; This range should match with PcdOvmfSecPageTablesBase and
> > -    ; PcdOvmfSecPageTablesSize which are declared in the FDF files.
> > +    ; This range should match with PcdOvmfSecPageTablesSize which is
> > +    ; declared in the FDF files.
> >      ;
> >      ; At the end of PEI, the pages tables will be rebuilt into a
> >      ; more permanent location by DxeIpl.
> > @@ -56,21 +57,21 @@ SetCr3ForPageTables64:
> >      mov     ecx, 6 * 0x1000 / 4
> >      xor     eax, eax
> >  clearPageTablesMemoryLoop:
> > -    mov     dword[ecx * 4 + 0x800000 - 4], eax
> > +    mov     dword[ecx * 4 + PT_ADDR (0) - 4], eax
> >      loop    clearPageTablesMemoryLoop
> >  
> >      ;
> >      ; Top level Page Directory Pointers (1 * 512GB entry)
> >      ;
> > -    mov     dword[0x800000], 0x801000 + PAGE_PDP_ATTR
> > +    mov     dword[PT_ADDR (0)], PT_ADDR (0x1000) + PAGE_PDP_ATTR
> >  
> >      ;
> >      ; Next level Page Directory Pointers (4 * 1GB entries => 4GB)
> >      ;
> > -    mov     dword[0x801000], 0x802000 + PAGE_PDP_ATTR
> > -    mov     dword[0x801008], 0x803000 + PAGE_PDP_ATTR
> > -    mov     dword[0x801010], 0x804000 + PAGE_PDP_ATTR
> > -    mov     dword[0x801018], 0x805000 + PAGE_PDP_ATTR
> > +    mov     dword[PT_ADDR (0x1000)], PT_ADDR (0x2000) + PAGE_PDP_ATTR
> > +    mov     dword[PT_ADDR (0x1008)], PT_ADDR (0x3000) + PAGE_PDP_ATTR
> > +    mov     dword[PT_ADDR (0x1010)], PT_ADDR (0x4000) + PAGE_PDP_ATTR
> > +    mov     dword[PT_ADDR (0x1018)], PT_ADDR (0x5000) + PAGE_PDP_ATTR
> >  
> >      ;
> >      ; Page Table Entries (2048 * 2MB entries => 4GB)
> > @@ -81,13 +82,13 @@ pageTableEntriesLoop:
> >      dec     eax
> >      shl     eax, 21
> >      add     eax, PAGE_2M_PDE_ATTR
> > -    mov     [ecx * 8 + 0x802000 - 8], eax
> > +    mov     [ecx * 8 + PT_ADDR (0x2000 - 8)], eax
> >      loop    pageTableEntriesLoop
> >  
> >      ;
> >      ; Set CR3 now that the paging structures are available
> >      ;
> > -    mov     eax, 0x800000
> > +    mov     eax, PT_ADDR (0)
> >      mov     cr3, eax
> >  
> >      OneTimeCallRet SetCr3ForPageTables64
> > diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
> > index 46610d243ecf..d1e5d4d9bdea 100644
> > --- a/OvmfPkg/ResetVector/ResetVector.inf
> > +++ b/OvmfPkg/ResetVector/ResetVector.inf
> > @@ -29,9 +29,14 @@ [Sources]
> >    ResetVector.nasmb
> >  
> >  [Packages]
> > +  OvmfPkg/OvmfPkg.dec
> >    MdePkg/MdePkg.dec
> >    UefiCpuPkg/UefiCpuPkg.dec
> >  
> >  [BuildOptions]
> >     *_*_IA32_NASMB_FLAGS = -I$(WORKSPACE)/UefiCpuPkg/ResetVector/Vtf0/
> >     *_*_X64_NASMB_FLAGS = -I$(WORKSPACE)/UefiCpuPkg/ResetVector/Vtf0/
> > +
> > +[Pcd]
> > +  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
> > +  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
> > diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
> > index 31ac06ae4a8c..29cbad367711 100644
> > --- a/OvmfPkg/ResetVector/ResetVector.nasmb
> > +++ b/OvmfPkg/ResetVector/ResetVector.nasmb
> > @@ -53,6 +53,13 @@
> >  %include "Ia32/SearchForSecEntry.asm"
> >  
> >  %ifdef ARCH_X64
> > +  #include <AutoGen.h>
> > +
> > +  %if (FixedPcdGet32 (PcdOvmfSecPageTablesSize) != 0x6000)
> > +    %error "This implementation inherently depends on PcdOvmfSecPageTablesSize"
> > +  %endif
> > +
> > +  %define PT_ADDR(Offset) (FixedPcdGet32 (PcdOvmfSecPageTablesBase) + (Offset))
> >  %include "Ia32/Flat32ToFlat64.asm"
> >  %include "Ia32/PageTables64.asm"
> >  %endif
> > 
> 
> I compared this patch to the one that I worked out / simplified from
> your v2 patch and posted as our shared v3:
> 
> https://lists.01.org/pipermail/edk2-devel/2016-November/004140.html
> 
> The differences are cosmetic.
> 
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> Tested-by: Laszlo Ersek <lersek@redhat.com>
> 
> I could commit & push this now (I could even find the energy in me for
> that), but I'd like Jordan to okay the patch as well, in this form.
> 

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>